The In Vivo Functionality Core is directed by Joseph Metzger. The major purpose of this core is to provide Nathan Shock Center (NSC) faculty with state-of-the art facilities and technical assistance in the in vivo physiological assessments of the aging rodent. This Core is uniquely positioned to offer NSC faculty members facilities and expert training for understanding the complex and adaptive gene-environment interactions in animals, including as examples, disease genes, genetic modifiers, nutrition, exercise, and stress, with a focus on aging and old animals. The Core facilities are fully operational, and over the past year the Core has provided services to 14 NSC faculty members. Cores include state-of-the-art equipment for high fidelity in vivo assessment of function such as, computerized food and drink monitoring system, metabolic chambers, six-lane treadmill, and Rota-rod. Also available are high thru-put analysis of blood pressure and EKG, as well as more precise and time-intensive instrumentation such as, in-vivo assessment of left ventricular cardiac performance by micromanometry catheters. Training and assistance are available for Core components. A surgical laboratory provides a convenient facility for researchers to perform surgical procedures on rodents. The Core has expert training in the operation of these platforms and also provides basic surgical techniques if needed. The Specific Aims are: Aim 1. To provide state-of-the-art facilities and instrumentation for the in vivo functional assessment of young and old mice, as well as to provide the necessary training in the use of the facilities and in the analysis of these highly complex data to Nathan Shock Center faculty who are determining the effects of aging on whole animal function. The Core will provide: (a) well-maintained, complex, state-of-the-art equipment, (b) training and assistance in the collection of reliable and valid data on appropriate measures of whole animal physiology, (c) analysis and presentation of the data, and (d) assistance with mechanistic interpretations of the data and integration of the interpretations into the manuscript. Aim 2. To provide expert training in rodent surgery procedures, instrumentation, and implantation, including both acute and recovery procedures, for the assessment of in vivo function in young and old animals.